According to the UK Health & Safety Executive's own statistics, slips, trips and falls on level ground consistently count for around 1 in 3 major injuries, and for over 1 in 5 injuries in workplace areas throughout Great Britain that result in a 3 day absence from work. The HSE statistics indicate that there are at least 35,000 injuries per annum due to slips, trips and falls and suggest that the majority of these accidents are slips.
Various factors contribute to slipping accidents, and the HSE have identified six factors considered to be of particular importance:                The nature of the floor        Contamination of the floor        Footwear considerations        Pedestrian factors        Cleaning        Environment        
The Workplace, (Health, Safety and Welfare) Regulations, 1992, require that floors must not be slippery, so as to expose any person to a risk to their safety. Methods have been developed for testing the inherent slipperiness of a floor surface, and two methods of measuring the slipperiness of a floor are referred to in HSE publications. These are the ‘pendulum Coefficient of Friction (CoF) test; and a surface micro-roughness meter test.
The pendulum coefficient of friction test is now the subject of a British Standard, BS 7976. The pendulum test instrument (TRL Pendulum Tester) uses an arm with a rubber shoe mounted on the end that swings from a fixed height. The contact arc chord length and depth are carefully controlled. The shoe is raised vertically against a spring that controls the pressure on the floor. Frictional engagement with the floor results in a loss of momentum and consequently so the swinging arm rises to a lower height at the end of the swing. A scale converts the reduced height into a coefficient of friction measurement.
Although the pendulum instrument is considered to provide an accurate assessment of the slipperiness of a floor in both dry and contaminated (e.g. wet conditions), it suffers from the drawback that it requires a skilled operative both to use it and to interpret the results. Moreover, according to the HSE, the pendulum meter is currently the only portable instrument that accurately simulates the action of a foot slipping on a wet floor.
The slipperiness of a floor may also be gauged by measuring the surface roughness of a flooring material. A number of types of roughness tests exist (see the HSE publication: ‘The assessment of pedestrian slip risk’ published by the Health and Safety Executive 10/04) and such methods, in theory, give a good indicator of floor slip resistance.
The surface micro-roughness meters measure a parameter known as the ‘Rz’ parameter which is calculated as the mean value of several peak-to valley measurements on the floor surface. According to the HSE, in most circumstances, both pendulum CoF and surface micro-roughness readings are required to give an accurate indicator of the slipperiness of a floor surface. The HSE classification of slip risk, based on pendulum measurements, classifies pendulum values of 0-24 as high risk, values of 25-35 as moderate risk, values of 36-64 as low risk and values of 65+ as extremely low risk.
The classification for Rz surface roughness (microns) states that a surface roughness of below 10 microns is classified as providing a high potential for slip, a surface roughness between 10 and 20 microns is classified as providing a moderate potential for slip, whereas a surface roughness of 20 or above is stated to provide a low potential for slip.
A major problem with the methods and instruments currently available for measuring the slipperiness of a floor is that, in practice, they require near laboratory conditions, and require setting up and data interpretation by skilled personnel. They are therefore not suitable for routine use and regular floor monitoring in an average work environment such as a supermarket where the condition of the floor, and hence its slipperiness, will typically fluctuate considerably, i.e. through changes in the type and extent of contamination of the floor, alteration of the floor substrate, changes in the cleaning personnel, change in the staff using the test equipment and poor statistical record monitoring. Therefore, at present, there remains a need for an apparatus that is simple to set up and use and which can be used by unskilled staff, i.e. staff that have little or no knowledge or understanding of slip causes or staff with only a minimum of training, to determine whether or not a floor is safe for the public to walk over.